Filtration systems are necessary to remove dirt and foreign matter from the water in swimming pools. Typically, filtration systems direct pool water through a filtering unit, which holds a porous filter bag for trapping any sediment and debris, while discharging the filtered water.
The filter bags used in filtering units are generally formed from a porous, nylon mesh material, which is cut and sewn into an appropriate bag shape, with an opening for attachment to the pool filter. Small particles of debris cannot be filtered out of the pool water by the mesh. Larger pieces of debris can attach to the stitching, thereby obstructing the flow of water out of the filter bag. Periodically the pool owner or operator must open the filter bag and remove the collected sediment and debris from the filter bag. Handling decaying debris, such as worms, dead bugs, and moldy leaves, can be unsanitary and unpleasant. The pool owner or operator must then clean the filter bag (or put a soiled one back on) before putting it back on the filtering unit. The cost of the filter bags presently being used dictates against replacing them with new ones until they are torn or worn out.